Cockroaches may give you the creeps but they are not dirty, according to Australian researchers.
This month’s Journal of Experimental Biology published their surprising results that illustrate how complex and sophisticated a cockroach’s immune system is.
The scientists from James Cook University in Townsville, Australia, we’re intrigued by the fact that some people react so strongly to these insects.
The researchers dissected 75 Blattella germanica, the most common species of cockroach in Australia, and removed the external surfaces of their bodies. They then measured how many phagocytes cells were inside their body cavities.
They found that those insects that appear cleaner (with fewer wax scales on their bodies) had more immune cells than dirtier ones.
“This is an extraordinary finding,” Dr. Luke McNally the lead researcher told ABC Science Online. “The results are contrary to what you would expect if these cells were simply a histamine response to foreign material.”
“Cockroaches have two different types of phagocyte present in their bodies, which we call ‘H’ cells and ‘P’ cells,” Dr. McNally said.
“The H cells are the same as we have in our own bodies; they attack foreign substances and remove them from the body cavity. “P” cells secrete histamine, which is associated with insecticide allergies.”
Why dirty would be clean
More immune cells mean that cockroaches can fight off more pathogens, Dr. McNally said.
“When you are confronted with a pathogenic organism, both the P cells and H cells come into action,” he explained. “P cells produce histamine which kills the invader, while H cells do not react to pathogens but work in concert with the immune system.”
“They bring all these phagocytes into the area, which increases the amount of killing that can occur,” he said. “In a way, it is like producing a lot more white blood cells in your body.”
“The important result was that cockroaches with fewer wax scales had higher H cell rates,” Dr McNally said.
These findings suggest that immune defense against pathogens is at least as important as defense against chemical toxins, he said.
“The H cell rate is all about how much killing can occur.”
Dr. McNally said the findings support his theory that cockroaches have a sophisticated immune system and are not just dirty scoundrels.
Clean enough to eat?
OK, so cockroaches aren’t as dirty an insect as we thought. Can I eat them?
“You could eat them if you were in a time of famine, but they taste bad,” Dr. McNally said. “They are about 80 percent water with a little bit of protein and carbohydrate.”
‘The only reason why you would want to eat them is that they are nutritious if nothing else is available,” he said. “But you would need to be starving.”
‘They have a high-fat content, which is unusual for an insect,” he said. “But you can’t really tell from their taste whether they are full of butter or not.”
Watch out next time you see one run across the kitchen floor or skitter into the corner at night, they might be trying to protect you from nasty germs!
As if we needed another reason to hate them…